This invention relates in general to systems which can cause a ground moving vehicle to lose momentum, can convert the momentum to potential energy, and can use that potential energy to re-accelerate the vehicle, and in particular to such systems which embody or work in conjunction with the braking system of the vehicle.
The prior art presents a wide variety of vehicular systems designed to capture and accumulate at least a portion of the momentum lost to a decelerating vehicle, and to use the accumulated energy to re-accelerate the vehicle. Except for flywheel systems, they all utilize various converters which in most cases convert the torque of a drive shaft somewhere between the prime mover (usually an internal combustion engine) and the axle of the vehicle drive wheels. This invention presents a novel and unique system of converting the torque to hydraulic pressure and then reconverting the pressure back to a positive moment to assist in the re-acceleration of the vehicle.
U.S. Pat. No. 3,892,283 by Johnson shows such a system which completely replaces the conventional drive train of a vehicle, including the power transmission. It discloses a variable displacement hydraulic pump/motor (p/m) with an output shaft differentially coupled to the axle of the drive wheels of a vehicle. The p/m is powered by an hydraulic pump driven by an engine or a pressurized hydraulic accumulator or both. The accumulator is charged by the pump during forward or idle conditions and by the p/m during braking. The rotation of the engine is entirely converted to hydraulic pressure, there is no solid state linkage to the differential drive shaft.
U.S. Pat. No. 3,910,043 by Clerk shows another system where the conventional drive train has been replaced by an all hydraulic system. In one embodiment, a single p/m drives the wheels through an output shaft and a conventional differential, and in a second embodiment the shaft and differential replaced by an all hydraulic transaxle comprising two p/ms. An internal combustion engine drives an hydraulic pump which powers the drive wheel p/m and also charges a flywheel accumulator. The accumulator incorporates a second hydraulic pump. The accumulator can drive the drive wheel p/m and conversely the drive wheels p/m can charge the accumulator during braking of the vehicle.
U.S. Pat. Nos. 4,227,587 and 4,350,220 by Carman show other all hydraulic systems. In both, a fixed displacement hydraulic p/m is coupled to the drive wheel axis of a vehicle. The axle p/m is powered by an hydraulic accumulator or an engine coupled p/m if the engine is running. The engine p/m is drivingly coupled to the engine and operates in pump mode when the engine is running and in motor mode to start the engine. When braking the axle p/m acts as a pump to pressurize the accumulator.
U.S. Pat. No. 4,132,283 by McCurry shows an hydraulic pump drivenly engaged by a clutch and gear means to an internal combustion engine crankshaft only when the vehicle is braking and the engine speed is above idle speed. The pump pressurizes an accumulator. An hydraulic motor is powered by the accumulator and is drivenly engaged by a clutch and gear means to the drive shaft abaft the transmission only when the vehicle is accelerating and the accumulator pressure is above a certain threshhold.
U.S. Pat. No. 4,351,409 by Malik shows a p/m selectively engaged by clutch, chain and sprocket means with an extension of an engine crankshaft forward of a conventional power transmission. An hydraulic pressure accumulator can be charged either by braking action or by the engine. The p/m unit is adapted to start the engine and supply drive to the wheels through the transmission.
U.S Pat. No. 4,441,573 by Carman et al. shows a variable displacement p/m used primarily for starting the engine, which is selectively engaged by clutch, sprocket and chains means with a clutched extension of an engine's crankshaft. Abaft the first p/m is a second p/m selectively engaged by clutch, sprocket and chain means to a one-way-clutched shaft which is a further extention of the engine's crankshaft. Abaft both p/ms is a torque converter (transmission).
All such prior devices and systems are cost prohibitive and cannot cost-effectively be installed in vehicles already manufactured. The reason for this is that the controls devised for such systems and devices are complicated, and the bulk and number of items needed is excessive. This invention presents a system which can be retrofitted onto an existing vehicle.
Other advantages and attributes of this invention will be readily discernible by the reading of the text hereinafter.